In an expansion mameiκmΦ\sum_m a_m e^{i\kappa m\Phi}, the chosen positive number κ\kappa is a carrier frequency parameter. The integer mm is the harmonic multiplier; κmΦ\kappa m\Phi is the full phase. This convention separates the common rapid oscillation scale from its .

Periodicity and physical scale

If Φ=pθ+Φ0\Phi=p\theta+\Phi_0 with θ\theta of period 2π2\pi and Φ0\Phi_0 independent of θ\theta, then eiκΦe^{i\kappa\Phi} is angularly periodic precisely when κpZ\kappa p\in\mathbb Z. The physical wavevector of harmonic mm is κmΦ\kappa m\nabla\Phi. A carrier parameter, a dyadic localization scale, and the physical wavenumber serve different roles.